libxl: domain restore: reshuffle, preparing for ao

We are going to arrange that libxl, instead of calling
xc_domain_restore, calls a stub function which forks and execs a
helper program, so that restore can be asynchronous rather than
blocking the whole toolstack.

This stub function will be called libxl__xc_domain_restore.

However, its prospective call site is unsuitable for a function which
needs to make a callback, and is buried in two nested single-call-site
functions which are logically part of the domain creation procedure.

So we first abolish those single-call-site functions, integrate their
contents into domain creation in their proper temporal order, and
break out libxl__xc_domain_restore ready for its reimplementation.

No functional change - just the following reorganisation:

* Abolish libxl__domain_restore_common, as it had only one caller.
  Move its contents into (what was) domain_restore.

* There is a new stage function domcreate_rebuild_done containing what
  used to be the bulk of domcreate_bootloader_done, since
  domcreate_bootloader_done now simply starts the restore (or does the
  rebuild) and arranges to call the next stage.

* Move the contents of domain_restore into its correct place in the
  domain creation sequence.  We put it inside
  domcreate_bootloader_done, which now either calls
  libxl__xc_domain_restore which will call the new function
  domcreate_rebuild_done, or calls domcreate_rebuild_done directly.

* Various general-purpose local variables (`i' etc.) and convenience
  alias variables need to be shuffled about accordingly.

* Consequently libxl__toolstack_restore needs to gain external linkage
  as it is now in a different file to its user.

* Move the xc_domain_save callbacks struct from the stack into
  libxl__domain_create_state.

In general the moved code remains almost identical.  Two returns in
what used to be libxl__domain_restore_common have been changed to set
the return value and "goto out", and the call sites for the abolished
and new functions have been adjusted.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/tools/libxl/libxl_save_callout.c b/tools/libxl/libxl_save_callout.c
new file mode 100644
index 0000000000..2f8db9f0b6
--- /dev/null
+++ b/tools/libxl/libxl_save_callout.c
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2012      Citrix Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ */
+
+#include "libxl_osdeps.h"
+
+#include "libxl_internal.h"
+
+void libxl__xc_domain_restore(libxl__egc *egc, libxl__domain_create_state *dcs,
+                              int hvm, int pae, int superpages,
+                              int no_incr_generationid)
+{
+    STATE_AO_GC(dcs->ao);
+
+    /* Convenience aliases */
+    const uint32_t domid = dcs->guest_domid;
+    const int restore_fd = dcs->restore_fd;
+    libxl__domain_build_state *const state = &dcs->build_state;
+
+    int r = xc_domain_restore(CTX->xch, restore_fd, domid,
+                              state->store_port, &state->store_mfn,
+                              state->store_domid, state->console_port,
+                              &state->console_mfn, state->console_domid,
+                              hvm, pae, superpages, no_incr_generationid,
+                              &state->vm_generationid_addr, &dcs->callbacks);
+    libxl__xc_domain_restore_done(egc, dcs, 0, r, errno);
+}